When I go out birding one of the things in my car or my pocket is a bottle of water, one of those smaller plastic bottles in which you can buy water. I refill it at our kitchen tap, or at the fountian in the nature center or wherever.
The fact that it takes about three liters of water to produce one liter of bottled water should be a compelling enough reason to avoid the waste of buying a new bottle.
Suggesting we live green is almost a cliche these days. But it will be absolutely necessary very soon. Start now.
Oh, and it you haven't bought your duck stamp yet your post office still has one for you.